Prior art arc welding torches often use collets for holding the welding electrode. Some collets are made in a tubular shape having an enlarged rear end which is pressed upon by a back cap. The collet is split longitudinally at two or more thin slots to allow the front end or tip of the collet to be compressed when the tip is forced against the interior conical shape of an adjacent sleeve which surrounds the collet tip. This compresion of the collet causes the collet to engage and hold the electrode.
The conical interior surface of the sleeve tends to center the collet within the sleeve. Usually the electrode is centered and touching only the collet thus causing all the electrical current to pass through the collet in order to reach the electrode. Because the collet is compressed against the electrode over a relatively small area, the current density is large and substantial heat is released. This heat causes the part of the electrode engaged by the collet to expand. The expanded electrode tends to stick in the collet making the electrode difficult to withdraw and adjust, which is needed when the electrode slowly disintegrates during welding. The difficulty in withdrawing the electrode often forces welders to remove the collet assembly from the torch. If the welder drops the electrode or collet this can lead to additional lost time and expense.
Prior art collets also tend to support the electrode in a somewhat unstable manner caused by movement of the collet within the torch head. This instability makes welding more difficult.
Prior art collets are costly to manufacture because of the machining of the thin slots or other configurations. Collets are often bored twice in the interior to limit the area over which the electrode is engaged by the collet. These machining steps are eliminated by the invention.
A further limitation of prior art collets is that they are not connected to the back cap. When the electrode is removed from the torch the back cap is unscrewed, the torch is rotated, and the collet and electrode are dumped out. Thus, the collet and electrode are often dropped or lost thus causing lost time or replacement of lost parts.